INDIANAPOLIS (WISH) – Leaders at Butler University have drafted a letter warning recipients of a possible breach of personal information.

In the notification letter obtained by 24-Hour News 8, the school’s president Jim Danko wrote that the university was contacted by authorities in California on May 28, 2014. Investigators alerted Butler that they had a suspect in custody who had a flash drive holding personal information of certain university employees.

Through an internal investigation, Butler officials discovered someone hacked the school’s network sometime between November 2013 and May 2014, the letter stated.

“Third-party computer forensics experts were retained by Butler University to confirm these findings and to identify the full extent of data potentially exposed as a result of this incident,” Danko wrote.

According to the school, the hacker(s) had access to files containing names, dates of birth, Social Security numbers and driver’s license numbers.

The university says approximately 163,000 people could be affected by the breach. That includes students, faculty and staff, and former and current applicants.

Butler has offered resources to people who think their personal information may have been compromised. The letter included an activation code to sign up for a complimentary membership to a fraud protection service called Experian. The code must be used by September 30, 2014. Butler has also established an assistance phone line staffed by professionals trained in identity protection and restoration, Danko said.

The assistance line could be reached Monday through Friday 9 a.m. to 7 p.m. A reference number of 8867061014 should be used when calling 888-414-8021.